Safety system for a traction kite with releasable adjustable bar stopper

ABSTRACT

A safety system for a traction kite comprises a central load bearing line and sliding control bar arrangement comprising a connection loop for connection to a harness hook, a system hub connecting the loop to the central load bearing line and a bar stopper located along the load bearing line towards the kite relative to the control bar. The bar stopper is retained to the system hub by a retainer which can be released by a primary safety quick release mechanism in such a way, that engaging the primary safety mechanism allows the control bar to slide along the central load bearing line towards the kite to reduce the power of the kite to a safe level.

TECHNICAL FIELD

The present invention relates to rider control systems for propulsive wings and sport traction kites. More particularly the present invention relates to a kite control bar stopper adjusting and retaining system that allows the rider to quickly and reliably adjust the bar stopper position and release the bar stopper to remove the power from the kite.

BACKGROUND ART

Using a kite for wind-driven propulsion of water, land, ice or snow-craft is highly effective and simple compared to other means of wind driven propulsion like sails and turbines. A kite can be constructed in such a way that all or most of the pulling force enters the craft in one point, without resulting momentum that can tip the craft over and without the requirements for rigid elements like masts, poles, and shafts connected to the craft. Kite are flying remote from the craft, in air layers with stronger winds, and can fly in figures across the sky in order to generate apparent wind, thus increasing the power. Thus, kite are very efficient as means to derive power from the wind.

Traction kites need to be manipulated constantly in order to control the flying trajectory of the kite to generate the required traction, to handle wind gusts and to keep the kite from falling to the ground. For smaller crafts, like buggies, surfboards and dinghies, the kite can be controlled by hand. One common way of manipulating the kite is by means of a 3 point control system, where one centrally placed line bears the main load of the kite, and two control lines are manipulated to sheet in and out the flexible left and right tips of the kite. In a common kite-setup the centrally placed line branches out towards the kite to multiple connection points at the leading edge of the kite. The centrally placed line attaches to a structural part of the craft, or, in case of surf style kiting where the rider stands on a wheeled or sliding board, to a point on a harness worn by the rider, and whereby the two control lines attach to the ends of a control bar.

The control bar often features a central hole through which the central load bearing line is slideably lead. In analogy to sheeting a sail on a sail craft, by sliding the bar away from the fixed point on the load bearing line, the tips of the kite are sheeted out, allowing the wind to pass the kites canopy, while sliding the bar towards the fixed point on the central load bearing line, the kite catches more wind and will thus power up. By pulling one side of the bar, the kite will sheet in on the side pulled, and out on the other. This will cause the kite to turn around the sheeted in side. The sliding motion or “stroke” of the bar is limited on one side by the assembly that attaches to the riders harness, and on the other by either the length of the rider's arms or parts of the control system. Most kite control systems feature a trim system that adjusts the length of the control lines relative to the trim line in order to allow compensation for stronger winds or larger kites, or to adjust to a riders personal style. Also, most kite control systems feature one or more safety options, which release power from the kite either by flagging the kite to the central load bearing line or a single line. Current surf kite control systems often feature a secondary safety line running parallel to the central load bearing line that attaches to a point on a line towards the kite such that if the kite is flown off that line, the kite will loose most or all of its power. In order to achieve this, the central load bearing line is by means of a quick release system disconnected from the harness, and the load is shifted to the secondary line which is connected to a safety leash on the harness.

A disadvantage of releasing the central load bearing line from the harness hook for emergency releasing is that the central load bearing line may at the moment of releasing carry a high pulling load. The release mechanism needs to be adapted to operate under these high loads. Releasing the kite like this can cause the control bar to shoot up in to the direction of the kite, not seldom causing the lines to twirl and tangle to a point that re-assembling the control system becomes too complicated for the situation of the rider. In some cases, just letting go of the kite is the only thing needed, in other cases, a temporary “full depower” of the kite is required, with a need to easily reassemble the kite.

Further, some kite control systems feature a dedicated bar stopper that limits the upstroke of the control bar. Some systems allow adjustment of the bar stopper position. The repeated movement of the control bar sliding over the central load bearing line usually causes wear on this line and in side the bar hole. Even though wear-resistant line is used, this wear can lead to breakage and therewith dangerous situations. A common way to reduce central load bearing line wear is by covering the line with slick wear resistant hard rubber tubing. Some surf kite control systems have the secondary safety line running outside the tubing, making it subject to wear, whereas some other have the secondary safety line running through the tubing, in which case measures need to be taken to avoid twisting of the main load bearing line and the secondary safety line internal to the tube. Running two lines through the tubing will obviously increase the internal diameter requirement. Such an increment of tube diameter requires a larger bar-hole and therewith a wider bar section, which is unfavourable for a good grip.

Although the use of tubing eliminates wear of the lines caused by rubbing of the control bar, sand and debris may accumulate inside the tubing, causing wear which is typically hidden from view as the current kite control systems with tubing don't allow easy access to the portion of the lines running inside the tubing. It needs to be mentioned that use of propulsive wings and traction kites involves a number risks, some of which already discussed above. Pilot error as well a material error can cause serious injury and even death as the forces produced by kites and quickly amount to dangerous levels. Designing kites and kite control systems needs to involve very serious failure analysis of every part.

DISCLOSURE OF INVENTION Technical Problem

The present invention overcomes the limitations and disadvantages present in the art by providing a design for a kite control system having a releasable bar stopper that allows for quickly and securely releasing of the bar stopper, which allows the control bar to move up the central load bearing line, thus de-powering the kite, without the need to disassemble the central load bearing line from the rider, and without the need for a secondary safety line. Further, the present invention incorporates a wear eliminating cover tubing with multiple discrete bar stopper positions, and a bar stopper that can be easily moved to a position of choice, as well as a simple method for exposing the length of central load bearing line inside the tubing for inspection.

While kites and kite control systems can have more than three lines near the fixed point on the vessel or rider, the invention is demonstrated primarily in a common 3 point control system comprising a central load bearing line and left and right control lines, each of which attached to the end of a control bar which slides over the central load bearing line.

The central load bearing line is therefore adapted with a connection loop for connecting the central load bearing line to a hook or another loop on a harness worn by the pilot or a fixed point on a vessel, a system hub comprising arrangements for connection of the central load bearing line to the connection loop, and a bar stopper arrangement that restrains the motion of the control bar to the section of line between the system hub and the bar stopper. The bar stopper is retained to the system hub by a retaining means which can be released by a primary safety quick release mechanism in such a way, that engaging the primary safety mechanism allows the control bar to slide along the central load bearing line towards the kite to reduce the power of the kite to a safe level.

The release control for the bar stopper is located on the system hub, as that is the easiest to reach. This implies a certain distance between the release control and the bar stopper. There are various methods available for remote releasing of the bar stopper, of which many can be feasible in different kite-setups, one can think of infra-red, induction or other relatively complex technologies, for the surf-style kiting and dinghies a better choice would be to keep it really simple, in order to reduce costs and to improve the system reliability in sometimes harsh conditions. A very simple way to retain the bar stopper would be by using a piece of cord, attached to the stopper at one side and releasably attached to the system hub on the other. This would have the disadvantage that the stopper retaining cord can go slack and hinder the operation of the kite control system. Such a cord would also wear quickly by the repeated movement of the control bar along the central load bearing line. A somewhat stiff element would not hinder the operation of the kite control system, especially when it is retained against the central load bearing line. A piece of hard rubber tubing, with the central load bearing line running inside of that tubing, would work very well while bringing further useful advantages to the system: Wear caused by friction between the central load bearing line and the central bar hole is eliminated, the central load bearing line can spin inside the tubing, and a closed, smooth tubing surface will not abrade the skin of the pilots fingers. A suitable material for such a tubing would be thermoplastic polyurethane (TPU), which is available in suitable grades and can be processed by common extrusion and moulding techniques. A major advantage of this material is its excellent bonding to other grades of TPU and many foreign materials in co-moulding or welding applications. Such a stopper retaining tubing can be adapted with a terminal block at the end towards the system hub, which can be received inside a pocket inside the system hub and locked by a latch. The bar stopper is attached to the end of the retaining tube directed at the kite, thus restraining the bar movement to the section of central load bearing line between the bar stopper and the system hub. Unlocking the latch releases the terminal block of the tubing and therewith the bar stopper. The tubing can slide up on the central load bearing line transporting the control bar along with it thus depowering the kite to a safe level. The terminal block can be provided with an alignment boss that aligns the connection loop with a corresponding slot in the control bar when the kite is flown un-hooked. Such a system hub should still be provided with a secondary safety release which can release the connecting loop from the fixed point on the harness or vessel, in order to provide two useful release options. The primary safety release allows to fully depower the kite instantly, and still be connected to the central load bearing line, thus allowing for easy re-assembly of the control system to sail on to a safer location if needed or to continue with the kite session. The secondary safety release resembles traditional kite safety systems in that it is prone to tangling while it does free the pilot from the kite if no further safety systems are in place. For surf-style kiting, safety systems usually deploy a kite-leash, which is connected to a point on the harness. In the present invention, such a leash can be attached to the end of the central load bearing line. By using the secondary safety release on the connection loop, the kite leash is still connected to the central load bearing line while the system hub, stopper retaining tube and control bar can slide up the central load bearing line. Usually the kite-leash is provided with a third safety release which frees the leash from the harness, in case the rider wants to let go of the complete kite.

Usual manoeuvring of a kite involves looping the kite, which as a result may twist the central load bearing line. Too many twists in the central load bearing line can have unwanted effects like wear and buckling on the kite control system and should therefore be avoided. Most kite control systems therefore include a swivel. The torque load resulting from a twisted line is often too low to make a swivel turn by itself, especially in surf conditions when sand and debris accumulate in every part of the control system. Manual untwisting is therefore preferred. The system hub can thereto have a swivelling retainer for the central load bearing line. In order to allow easy untwisting in all conditions a thrust ball bearing can be included. The stopper can be attached to the retaining means either in a fixed position or in a way it can lock in different positions, in order to allow the pilot to adapt the bar stroke to different circumstances or riding styles. The locking can be achieved either by friction between the retaining means and the stopper or by a discrete locking arrangement, for instance by adapting the retaining means with two or more ridges, and the stopper assembly with corresponding locking means. Such a stopper assembly can be operated manually, for in stance by simultaneously disengaging the locking means and sliding the stopper assembly along the retaining means to a new position.

In case the retaining means is provided as a section of hard rubber tubing, locking by mere friction can be unreliable as the amount of friction can be influenced by temperature, moisture and material deformation induced by the forces on the stopper assembly. In a preferred embodiment according to the present invention, a stopper assembly is provided with a stopper body having one or more locking fingers, and, towards the control bar, a sensor ring, which sensor ring is adapted with a chamfered inner edge. When the bar pushes against the sensor ring, the chamfered inner edge will slide over the outer tips of the locking fingers thereby reducing the inner diameter of the contour described by the locking fingers. This will incur pressure of the locking finger on the retainer tubing and therewith increase the friction between the bar stopper assembly and the retaining means. To further ensure good grip from the stopper on the retaining means, two or more ridges that can interlock with the locking fingers and have a narrower diameter than the control bar centre hole can be made on the retaining means, thus providing multiple positive locking positions. The bar stopper body and the sensor ring can be loosely connected with an elastic sleeve. To move the bar stopper assembly towards the kite, it can be picked up and move up the retainer tube, to move the stopper assembly towards the connecting loop, the bar stopper assembly can be picked up at the sensor ring. This way the locking fingers can flex aside when they pass the ridges on the retainer tubing, allowing the stopper assembly to pass a ridge in both directions.

Thus, the present invention involves providing a very simple releasable bar stopper retaining system that offers multiple safety release methods to instantly depower the kite in order to allow the pilot to choose the appropriate safety choices depending on the type of emergency, an effective and secure protection of the central load bearing line against wear, and an easily operated position adjustable bar stopper.

Solution to Problem Technical Solution Advantageous Effects of Invention Advantageous Effects

BRIEF DESCRIPTION OF DRAWINGS Description of Drawings

FIG. 1 depicts a kite with its control system, featuring a releasable bar stopper retainer according to the present invention, in a normal flying situation.

FIG. 2 depicts a kite with its control system, featuring a releasable bar stopper retainer according to the present invention, after re leasing the bar stopper retainer.

FIG. 3 depicts a kite control system provided with a releasable bar stopper retainer according to the present invention, in a normal flying situation.

FIG. 4 depicts a kite control system provided with a releasable bar stopper retainer according to the present invention, after releasing the bar stopper retainer.

FIG. 5 depicts a cross section of the system hub of a kite control system provided with a releasable bar stopper retainer according to the present invention, in a normal flying situation.

FIG. 6 depicts a cross section of the system hub of a kite control system provided with a releasable bar stopper retainer according to the present invention, after releasing the bar stopper retainer.

FIGS. 7. 8 and 9 depict the system hub and connecting loop of a kite control system provided with a releasable bar stopper retainer according to the present invention, after releasing connecting loop safety, whereby FIG. 7 is partially sectioned, in different stages of the releasing.

FIG. 10 depicts an adjustable bar stopper in its adjusting position, with a part of the cover removed to show internal parts.

FIG. 11 depicts a cross section of an adjustable bar stopper in adjusting position.

FIG. 12 depicts a cross section of an adjustable bar stopper when engaged in a locking position.

BEST MODE FOR CARRYING OUT THE INVENTION Best Mode MODE FOR THE INVENTION Mode for Invention

The present invention is further demonstrated by FIG. 1. A kite 1, with anchoring means 2, is provided with a typical 3-point control system which has multiple lines 3 attached to the forward edge which converge in to a central load bearing line 4 which attaches to the anchoring means 2, where the length of the lines 3 and central load bearing 4 together define length A, and two control lines SL and SR, attached to both ends of the trailing edge, each attached to one end a control bar 6. The bar is provided with a centrally placed hole 7 through which the central load bearing line can slide. A releasable adjustable bar stopper 8 according to the present invention is attached to a retaining means 9 and situated between the control bar 6 and a stopper ball 10. The retaining means attaches releasable to a system hub 11 of the anchoring means, provided with a release cuff 12. In general use, the flying kite is controlled by movement of the bar 6 relative to the anchoring means 2. Sliding the bar 6 over the central load bearing line 4 in a direction away from the anchoring means 2 results in the kite assuming a position with less projected area towards the wind, while pulling the bar towards the anchoring means gradually increases the projected area towards the wind giving the kite more lift and therewith more tension on the lines 4 and 5. Holding the bar skewed shortens one of the control lines 5 relative to the other, which results in the kite turning in the air. The total sliding movement of bar 6 relative to the anchoring means 2 over the central load bearing line 4 needed to fully control flying of the kite defines the bar stroke. Kite pilots typically wish to limit this bar stroke according to the conditions they are flying the kite in, or to perform certain manoeuvres. For instance, a surf style kiter wants to have a long bar stroke when walking on the shore with the kite in the air, in order to safely handle gusts. Or, another surf style kiter wants to set a short bar stroke to remove pressure from the bar when sailing a long tack. Thus, a reliable and easy to adjust bar stopper is required. The bar stopper retaining means is thereto adapted with an array of ridges 13.

FIG. 2 demonstrates the kite after the bar stopper retainer is released by pushing out the bar stopper release cuff 12. The retainer can now move freely over the central load bearing line 4 and will be pulled towards the kite by the control line tension. The kite preferably has an arrangement in the plurality of lines 3 that allows the kite to flag all or most of its power when it is suspended by the central load bearing line. The stopper ball 10 stops the retainer movement at a point that allows sufficient slackening of the control lines 5.

Upon pushing out the bar stopper release cuff 12, the central load bearing line is still connected to the anchoring means 2, which makes re-assembly of the safety system an easy job. Considering a surf style kiter who is out on open water, this is of eminent importance if he needs to return to shore after an emergency kite landing. By pulling in the central load bearing line 4, the bar stopper retainer 9 can be pulled towards and locked in system hub 11. System hub 11 is preferably made from a tough injection moulded plastic like polyamid 6.6, so that the entire functional geometry can moulded in a single process, and the typical flexibility can be applied to incorporate functions that require some movement.

FIG. 3 depicts a larger view of the kite control system and the bar stopper retainer according to the present invention. For normal kite flying, the control bar 6 can slide over the bar stopper retainer 9 between its connection to the system hub 11 and the bar stopper 8. In this embodiment of the invention, the bar stopper retainer is made as a hard rubber tube, with the ridges 13 and a terminal block 14 adapted with an alignment boss 15 welded on to it.

FIG. 4 also depicts a larger view of the kite control system and the bar stopper retainer according to the present invention, now in the same state as shown in FIG. 2.

In FIG. 5, a cross section of the anchoring means is shown, in more detail and revealing some internal parts. The terminal block 14 has two parts, the actual retaining block which is held to the system hub 11 by means of two slightly flexible locking fingers 16, which are embraced by the bar stopper release cuff 12. Further, the central load bearing line 4 is shown, which is at its end looped around a D-ring 17, which is linked to a swivel 18 by a link line 19. A kite safety leash 20 is connected by a carabiner 21 to the swivel 18 at one end, and to the kite pilot's harness hook 22 or a point on the vessel on the other end. Swivel 18 serves to avoid twisting of the kite safety leash. Also, a safety pin 23 made from hard rubber tubing is shown, which is typically inserted in a loop in harness hook 22 to avoid the anchoring means 2, in this embodiment connection loop 24, from falling from harness hook 22. Some surf-style kiters prefer to kite without the safety pin to allow them to perform un-hooked manoeuvres as seen in wake-style kiting or advanced surf riding. D-ring 17 is snap-locked inside turning knob 25 in such a way that pulling the system hub towards the kite releases the snap-lock and transfer the load of the load bearing line 4 to the kite safety leash. This happens if connection loop 24 is no longer connected to the harness hook 22. Turning knob 25 is seated against a thrust ball bearing 26 to ensure smooth turning if the central load bearing line is twisted. As long as there is only limited buildup of sand, salt and debris inside the system hub 11, the central load bearing line 4 can unspin by itself.

FIG. 6 depicts release of the bar stopper retainer after pushing out release cuff 12. In this embodiment, the release cuff is adapted with cams 27, which slide over bosses 28 on the snap fingers 16 and force the snap fingers 16 to open up when the release cuff 12 is pushed away from system hub 11. Pushing out of release cuff 12 also releases the embrace of the snap fingers, so bar stopper retainer 9 is at that point released.

FIG. 7 shows the anchoring means 2 in a frontal view, partly sectioned to show how the connection loop 24 is retained by release tab 29 preferably made from stainless steel, which holds a core line 30 from the connection loop 24 around a stainless steel pin 31, which tab is in turn retained by connection loop release cuff 32, which slideably embraces both a fixed a leg 33 of system hub 11 and release tab 29. Connection loop release cuff 32 is held to the system hub by an elastic cord (not shown in the figures) to ensure it stays in the embracing position.

FIG. 8 shows how by sliding connection loop release cuff 32 in a direction away from the system hub, release tab 29 is no longer embraced by the connection loop release cuff 32, allowing it to swing to a position co-linear with the connection loop end, and slide past stainless steel pin 31. At that point, the connection loop is open and can release from harness hook 22.

FIG. 9 shows how D-ring 19 is released from turning knob 25, allowing the system hub and therewith the bar stopper retainer 9 so slide up on the central load bearing line 4, while the load on the load bearing line 4 is transferred to the kite-leash 20. This secondary safety release is different from the primary safety release as provided by releasing the bar stopper retainer as depicted in FIGS. 2, 4, and 6, in that the anchoring means 2 are now released from the pilot or vessel, and only linked by the kite-leash. Kite-leashes are typically adapted with another, third, release system, which needs to be deployed to fully remove the kite from the pilot or vessel. This is only necessary in case the other releases fail, or when circumstances require such a third release, for instance when a kite has landed between big waves—these can rip the kite canopy if the kite is still connected to the rider.

FIG. 10 depicts a position adjustable bar stopper 8 with a part of its cover opened to show some of the internal components. The bar stopper 8 comprises two preferably plastic parts situated around bar stopper retainer 9, a diaphragm ring 34 and a sensor ring 35, held together by a flexible neoprene sleeve 36 which is retained to diaphragm 34 and sensor ring 35 by means of two straps 37 in such a way, that diaphragm ring 34 and sensor ring 35 can move towards each other. Diaphragm ring 34 is adapted with a circular array of flexible locking fingers 38, which on their outer perimeter are conically shaped. In their relaxed position, the locking fingers 38 together have an inner diameter slightly larger than the outer diameter of the ridges 13 of tubular bar stopper retainer 9, so that it can slide over ridges 13. In order to position bar stopper 8, it can slide up and down over bar stopper retainer 9 until it is located over the ridge where the pilot wants to limit the bar stroke to. Diaphragm ring 34 is further adapted with two supports 39 for friction 0-ring 40, which presses against the stopper retainer 9 in order to retain the bar stopper assembly on the set position of the bar stopper retainer 9.

FIG. 11 shows a cross section through bar stopper 8 in basically the same position as Figure I 0. Sensor ring 35 has a chamfered inner edge 41 that corresponds with the conically shaped ends of the locking fingers 38. By applying pressure on the sensor ring 35 towards the diaphragm ring 34, for instance the control bar 6 being pulled toward the kite by control lines 5, like shown in FIG. 12, the locking finger 38 are moved towards the centre line of bar stopper retainer 9, therewith reducing the inner diameter collectively formed by locking fingers 38, thus locking the bar stopper 8 against the one of the ridges 13. Thus, the releasable adjustable bar stopper according to the present invention allows the rider to quickly and reliably adjust the bar stopper position and release the bar stopper to remove the power from the kite while providing further safety options and improvements to the durability of kite control system, which can be economically manufactured in a clean and compact design.

INDUSTRIAL APPLICABILITY Sequence Listing Free Text

Sequence List Text 

1. A safety system for a traction kite comprising a central load bearing line and sliding control bar arrangement said safety system comprising a connection loop for connection to a harness hook, a system hub connecting said connection loop to said central load bearing line and a bar stopper located along the load bearing line towards the kite relative to the control bar, wherein the bar stopper is retained to the system hub by a retaining means releasable by a primary safety quick release mechanism in such a way that engaging the primary safety mechanism allows the control bar to slide along the central load bearing line towards the kite to reduce the power of the kite to a safe level.
 2. The safety system according to claim 1 wherein the safety quick release mechanism is built in to the system hub for easy access.
 3. The safety system according to claim 1 wherein the bar stopper can be placed in different positions along the retaining means.
 4. The safety system according to claim 3 wherein the retaining means features an array of two or more ridges for locking the stopper position.
 5. The safety system according to claim 4 wherein the retaining means is an oblong element arranged along the central load bearing line.
 6. The safety system according to claim 5 wherein the retaining means is a tubular element arranged about the central load bearing line.
 7. The safety system according to claim 6 wherein the retaining means has a retaining block which is locked in a receiving pocket inside the system hub by a releasable latch.
 8. The safety system according to claim 7 wherein retaining means release system can be set to automatically release when the pulling force of the bar against the bar stopper reaches a certain threshold load.
 9. The safety system according to claim 8 wherein the retaining means is provided with an alignment boss that aligns the connection loop with a corresponding slot in the control bar when the kite is flown un-hooked.
 10. The safety system according to claim 9 wherein the connecting loop can be opened by a secondary safety quick release mechanism.
 11. The safety system according to claim 10 wherein the system hub features a trim system to adjust the length of the central load bearing ling relative to the control lines.
 12. The safety system according to claim 11 wherein the system hub features a trim system to adjust the length of the central load bearing ling relative to the control lines.
 13. The safety system according to claim 12 wherein the retaining element is formed like a turning knob that allows the pilot to manually untwist the central load bearing line. 